Wireless communication is widely used all over the world and greatly facilitates communication between people. The wireless communication can provide various services, including voice conversation, web page download, and the like. A typical wireless communications system or network such as a Long Term Evolution (LTE) system provides a radio link for multiple user equipment (UE) in a cellular cell by using a base station device to implement wireless communication. A shared radio spectrum is generally used in this wireless connection. As shown in FIG. 1, FIG. 1 is a schematic diagram of a wireless communications system. A base station device provides a wireless data communication service for multiple UEs (two UEs given in the figure) by using a same radio frequency band. Data downloaded by a UE from a server reaches the base station device through the Internet, a packet data network gateway (P-GW), and a serving gateway (S-GW), and is transmitted by the base station device to the UEs. Different from a conventional second-generation wireless communications system such as a Global System for Mobile Communications (GSM), the LTE system supports only a packet switching (PS) connection, and does not support a circuit switching (CS) connection any more. The CS connection requires resource reservation to ensure data transmission. Even if a transmit end does not have data that needs to be transmitted, a reserved resource cannot be released. The PS connection does not require resource reservation, and therefore can improve utilization efficiency of a radio spectrum. To provide different quality of service (QoS), the LTE system maps different services to different tunnels, so as to implement different processing. Nine different QoS characteristics are defined in the LTE. A guaranteed bit rate (GBR) service corresponding to a QoS class identifier (QCI) that is equal to 1-4 can provide a minimum rate guarantee. For example, a conventional voice service can provide a guaranteed voice transmission rate. In this way, speech quality of two parties of a call can be ensured and meaning expression of the call cannot be misunderstood. A non-GBR service (for example, QCI is equal to 6-9) does not provide the minimum rate guarantee. Therefore, in actual system running, a rate of the non-GBR service may be excessively low, causing poor user experience. For example, when a non-GBR type whose QCI=7 is used in a communication connection of a voice user, compared with a conventional voice of a GBR service whose QCI=1, in this case, a communication rate of both parties of a call may be much lower than an average rate that needs to be guaranteed in a normal call. Consequently, a recipient of the call may obviously feel a phenomenon such as a call delay and an unclear voice, and conversation experience is also relatively poor. A communication rate is lower than a required minimum rate and a service stream cannot be smoothly transmitted, and as a result congestion may occur in an access network.
In conclusion, a problem that needs to be resolved currently is how to control congestion in an access network to ensure smooth communication.